Insulating glass units with low-e and antireflective coatings, and/or methods of making the same

ABSTRACT

Certain example embodiments of this invention relate to insulating glass (IG) units including three substantially parallel spaced apart glass substrates, wherein at least two of the surfaces include low-emissivity (low-E) coatings and at least some of the non-low E coated surfaces have antireflective (AR) coatings disposed thereon. In certain example embodiments, low-E coatings are provided on the second and fifth surfaces of the IG unit, and each internal surface of the IG unit that does not support a low-E coating does support an AR coating. Additional AR coatings may be provided on one or both of the outermost surfaces in certain example embodiments. In some cases, the center substrate need not be heat treated because of the reduced absorption enabled by providing the low-E coatings on the two outermost substrates, as well as the reduced heat accumulation in the center lite itself and in the two adjacent spacers.

FIELD OF THE INVENTION

Certain example embodiments of this invention relate to insulating glassunits (IGUs or IG units) with low-emissivity (low-E) and antireflective(AR) coatings, and/or methods of making the same. More particularly,certain example embodiments relate to IG units including threesubstantially parallel spaced apart glass substrates, wherein at leasttwo of the surfaces include low-E coatings and at least some of thenon-low E coated surfaces have AR coatings disposed thereon.

BACKGROUND AND SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

Insulating glass units (IGUs or IG units) are known in the art. See, forexample, U.S. Pat. Nos. 6,632,491; 6,014,872; 5,800,933; 5,784,853; and5,514,476, and also U.S. Publication No. 2007/0128449, the entirecontents of each of which are hereby incorporated herein by reference.

Insulating glass units generally include two panes, sheets, substrates,or lites of glass in substantially parallel spaced apart relation to oneanother, with an optionally gas filled pocket therebetween. As shown inFIG. 1, first and second substrates 10 a and 10 b are sealed togetherthrough the use of seals/spacers 12 around the edges of the twosubstrates 10 a and 10 b. The sealing components in a conventional IGunit may include both a sealer component and a spacer component. Thespacer component may act to support the weight of the substrates byholding them apart (and thus forming a gap therebetween).

The seals sometimes may act to hold the substrates together. In certaininstances, these edge seals may be hermetic seals. The use of hermeticseals may allow for the gap between the substrates to be filled with agas. In certain conventional IG units, a desiccant may be exposed to theinterior gap between the substrates. The desiccant may act to keep thisinterior gap dry (e.g., decrease condensation).

Once sealed, the IGU is formed and may be installed in a commercial,residential, or other setting, e.g., as an energy saving window. Incomparison to a single paned window, a standard double paned window mayhave an R-value more than 2. IG units may have yet higher R-values.Additional techniques may be used to yet further increase the R-value ofa window. On conventional technique involves disposing a low-E coating14 (e.g., as shown in FIG. 1) to a surface of one of the substrates.Another technique involves tinting the glass substrates. Some techniquesmay be applied to decrease the heat transference over the gap betweenthe two substrates 10, for example, by creating a vacuum or near-vacuumbetween the two panes of glass or filling the gap with an inert gas suchas argon. As is known, R-values are measures of thermal resistance andmay be obtained by for an entire section of material by dividing theunit thermal resistance by the cross-sectional area of the depth of thematerial or assembly. The overall heat transfer coefficient, or U-value,is the inverse of the R-value, and describes how well a building elementconducts heat.

New techniques of reducing heat transference are continually soughtafter in order to improve, for example, the energy efficiency ofwindows. Also, new techniques in making IG units are also continuouslysought after for reducing the overall cost of the IG unit. HigherR-values and thus lower U-values typically correspond to more energyefficient materials. Thus, it will be appreciated that when designingmore energy efficient windows, it would be desirable to provide reducedU-values to correspondingly reduce heat losses through the window frominside to outside (in cold regions). In addition, it also would bedesirable to provide a high and neutral visible transmission (Tvis) anda high solar heat gain (solar factor or g-value), thereby making itpossible for solar radiation to pass through the window to heat up theroom indoor (e.g., on cold days).

Heat losses caused by convection and thermal conduction may be reducedby optimizing the gas and the spacer width. However, a significant partof thermal losses is caused by heat radiation. To reduce this kind ofloss, the emissivity of at least one surface of the IGU has to bereduced, which can be achieved by low-E coatings, as alluded to above.Because these coatings in general are very sensitive to humidity andother environmental conditions, low-E coatings typically are applied toat least one surface oriented towards the sealed spacer filled with thenoble gas.

Unfortunately, for physical reasons, it is difficult to lower theU-value while keeping the visible transmission and g-value at theiroriginal levels. For example, when attempting to lower the U-value bycoating more surfaces or by modifying the coating, visible transmissionand g-values are typically decreased. Typical performance data fordouble glaze IGUs is shown in the table below. The data in the tablebelow has been simulated for IGUs including two sheets of 4 mm thickfloat glass, 90% argon filled cavities spaced apart with 16 mm spacers,and having their third surface coated with a low-E coating. As can beseen from the table below, it is possible to achieve an emissivity of2%, which leads to a U-value achievable by an Ar-filled double glaze IGUof 1.0 W/m²K.

U-value T_(vis) g-value Performance (W/m²K) (%) (%) Product with 4%emissivity 1.2 80 66 Product with 3% emissivity 1.1 79 63 Product with2% emissivity 1.0 70 53

As can be seen, the visible transmission and g-value drop at this lowestreported emissivity level. As is know, new regulations in Europe, forexample, will go into effect that will require U-values even lower than1.0 W/m²K. Conventional approaches for reducing the U-value yet furthermay result in unacceptable visible transmission and g-value losses and,in fact, sometimes may not even be possible or feasible in all cases.

Thus, it will be appreciated that there is a need in the art forimproved window glazings that have yet further reduced U-values whilestill maintaining acceptable visible transmission and g-value.

In certain example embodiments of this invention, an insulating glass(IG) unit is provided. First, second, and third substantially parallelspaced apart glass substrates are provided, with the first substratebeing an outermost substrate and the third substrate being an innermostsubstrate. A first spacer system is disposed around peripheral edges ofthe first and second substrates, with a first cavity being definedbetween the first and second substrates. A second spacer system isdisposed around peripheral edges of the second and third substrates,with a second cavity being defined between the second and thirdsubstrates. First and second low-emissivity (low-E) coatings aredisposed on interior surfaces of the first and third substratesrespectively such that the first and second low-E coatings face oneanother. First and second antireflective coatings are disposed onopposing major surfaces of the second substrate. Each said low-E coatingcomprises, in order moving away from the substrate on which it isdisposed: a layer comprising titanium oxide, a layer comprising zincoxide, an infrared reflecting layer comprising silver, a layercomprising a metal, oxide, or sub-oxide of Ni and/or Cr, a layercomprising tin oxide, and a layer comprising silicon nitride.

In certain example embodiments of this invention, an insulating glass(IG) unit is provided. First, second, and third substantially parallelspaced apart glass substrates are provided, with the first substratebeing an outermost substrate and the third substrate being an innermostsubstrate. First and second low-emissivity (low-E) coatings are disposedon interior surfaces of the first and third substrates respectively suchthat the first and second low-E coatings face one another. Each saidlow-E coating includes at least one Ag-based infrared (IR) reflectinglayer sandwiched between one or more dielectric layers. First and secondantireflective coatings are disposed on opposing major surfaces of thesecond substrate. The first and third substrates are heat treated andthe second substrate is not heat treated.

In certain example embodiments of this invention, a method of making aninsulating glass (IG) unit is provided. First, second, and third glasssubstrates are provided, with the second substrate supporting first andsecond antireflective (AR) coatings on opposing major surfaces thereof.The first substrate supports a first low-emissivity (low-E) coating onone major surface thereof, and the third substrate supports a secondlow-E coating on one major surface thereof. The first, second, and thirdsubstrates are oriented in substantially parallel spaced apart relationto one another using first and second spacer systems, with the firstspacer system being located around peripheral edges of and spacing apartthe first and second substrates, and with the second spacer system beinglocated around peripheral edges of and spacing apart the second andthird substrates. The first substrate is an outermost substrate and thethird substrate is an innermost substrate. The first and second low-Ecoatings are disposed on interior surfaces of the first and thirdsubstrates respectively such that the first and second low-E coatingsface one another. Each said low-E coating comprises, in order movingaway from the substrate on which is disposed: a layer comprisingtitanium oxide, a layer comprising zinc oxide, an infrared reflectinglayer comprising silver, a layer comprising a metal, oxide, or sub-oxideof Ni and/or Cr, a layer comprising tin oxide, and a layer comprisingsilicon nitride.

In certain example embodiments of this invention, a method of making aninsulating glass (IG) unit is provided. A first low-emissivity (low-E)coating is disposed on a first substrate. First and secondantireflective (AR) coatings are disposed on opposing major surfaces ofa second substrate. A second low-E coating is disposed on a thirdsubstrate. Either (a) the first, second, and third substrates are builtinto an IG unit, or (b) the first, second, and third substrates areforwarded to a fabricator to be built into an IG unit. In the built IGunit, the second substrate is sandwiched between the first and thirdsubstrates such that the first and second low-E coatings face oneanother.

The features, aspects, advantages, and example embodiments describedherein may be combined to realize yet further embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages may be better and morecompletely understood by reference to the following detailed descriptionof exemplary illustrative embodiments in conjunction with the drawings,of which:

FIG. 1 is a cross-sectional view of a conventional insulating glassunit;

FIG. 2 shows a triple glaze IGU that includes low-E coatings on surfaces3 and 5, in accordance with certain example embodiments;

FIG. 3 shows a triple glaze IGU that includes low-E coatings on surfaces2 and 5, in accordance with certain example embodiments;

FIG. 4 plots percent reflectance versus wavelength for AMIRAN(TRADEMARK) coated glass provided by Schott provided on both surfaces ofa 4 mm thick piece of float glass;

FIG. 5 is an example low-E coating that may be used in connection withcertain example embodiments; and

FIG. 6 is an example four-layer heat treatable sputter deposited ARcoating that may be used in connection with certain example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Certain embodiments of this invention relate to insulating glass (IG)units including three substantially parallel spaced apart glasssubstrates, wherein at least two of the surfaces include low-emissivity(low-E) coatings and at least some of the non-low E coated surfaces haveantireflective (AR) coatings disposed thereon. In certain exampleembodiments, low-E coatings are provided on the second and fifthsurfaces of the IG unit, and each internal surface of the IG unit thatdoes not support a low-E coating does support an AR coating. AdditionalAR coatings may be provided on one or both of the outermost surfaces incertain example embodiments. In some cases, the center substrate neednot be heat treated because of the reduced absorption enabled byproviding the low-E coatings on the two outermost substrates, as well asthe reduced heat accumulation in the center lite itself and in the twoadjacent spacers. It therefore is possible to advantageously provide incertain example embodiments lower U-values, together with higher visibletransmission and g-values.

One approach for achieving window units with low U-values (e.g.,U-values less than or equal to 1.0 W/m²K) involves providing anadditional spacer and an additional low-E coating in connection with anadditional substrate. Thus, certain example embodiments may provide aso-called triple glaze IGU. Compared with a conventional double glazeIGU, however, two additional surfaces are reflective. Each new surfacereflects about 4% of the visible and about 2% of the near infraredspectrum, thereby reducing Tvis and the solar factor yet further.Consequently, the total reflectance of the triple glaze IGU is increasedby about 8% points and visible light transmittance and solar factor arereduced. Thus, certain example embodiments may incorporate additionalantireflective coatings (AR coatings) on one, two, or more additionalsurfaces in triple glaze IGUs. Lower U-values may be achieved with theadditional spacer and an additional low-E coating, while enablingvisible light transmittance and solar factor to be kept at higher valuesby taking advantage of the AR coatings.

Certain example embodiments may incorporate low-E coatings on two of thesix available surfaces. FIGS. 2 and 3 show two examples that eachinclude first, second, and third substrates 20 a, 20 b, and 20 c. Thefirst substrate 20 a is oriented closest to the exterior of thebuilding, whereas the third substrates 20 c is oriented closest to theinterior of the building. One or more gasses (e.g., one or more inertgasses such as Argon, Krypton, SF₆, or the like, with or without oxygenor the like) may be disposed in the cavities formed between adjacentsubstrates.

Both FIGS. 2 and 3 include first and second low-E coatings 24 a and 24b. However, in FIG. 2, the low-E coatings are provided on surfaces 3 and5 (the outwardly facing surfaces of the second and third substrates 20 band 20 c), whereas the low-E coatings are provided on surfaces 2 and 5(the inner facing surface of the first substrate 20 a and the exteriorfacing surface of the third substrate 20 c) in the FIG. 3. Spacers 22help maintain the substrates in substantially parallel spaced apartrelation to one another.

AR coatings 26 are provided on one or more surfaces where the low-Ecoatings are not provided. Thus, in the FIG. 2 example embodiment,first, second, third, and fourth AR coatings 26 a, 26 b, 26 c, and 26 dare provided on surfaces 1, 2, 4, and 6. As can be seen, then, incertain example embodiments, the AR coatings may be provided on everysurface that does not support a low-E coating thereon. In other exampleembodiments, however, AR coatings may be provided on a partial subset ofthe surfaces on which low-E coatings are not provided. For example, incertain example embodiments, low-E coatings may be present on everyinterior surface that a low-E coating is not present on, but may or maynot be provided to outer surfaces. In this latter respect, the FIG. 3example embodiment shows AR coatings 26 a, 26 b, and 26 c provided onthe first, third, and fourth surfaces of the assembly.

Once again referring to FIG. 2, it can be seen that this example tripleglaze IGU includes low-E coatings on surfaces 3 and 5, in accordancewith certain example embodiments. Providing low-E coatings on surfaces 3and 5 has been found to result in the best solar factors or g-values. Inthis case, surfaces 1, 2, 4, and 6 become available for AR coatings.

Although this arrangement has a high solar factor, several disadvantagesappear. These disadvantages include, for example, an increased risk ofthermal breakage of the center lite. The increased risk of thermalbreakage is believed to be related to the absorption within the low-Ecoating, as well as heat accumulation in the lite itself and in the twoadjacent spacers. AR coating both surfaces of the first lite (surfaces 1and 2) is efficient by dip coating (e.g. via sol gel processes) isefficient, inasmuch as both surfaces can be coated in one dip coatingprocess. Unfortunately, however, surfaces 1 and 6 of the triple glazeIGU are exposed to the atmosphere (e.g., building exterior and interior,respectively). These coatings may be contaminated or damaged by virtueof this exposure, via normal cleaning processes, etc. Of course, low-Ecoatings may be provided on surfaces 3 and 5 in different embodiments ofthis invention, e.g., where these issues are of a reduced concern.

The only surfaces that are available for AR coatings and that areprotected from the outside and inside atmosphere are surfaces 2 and 4.Surface 2 might be coated, although dip coating is inefficient becausesurface 1 may have to be covered during the process (to avoid having anAR coating facing the outside atmosphere and overlying the low-Ecoating). A similar situation arises when coating surface 4 with an ARlayer, e.g., as surface 3 may have to be covered. Additionally, duringsubsequent low-E coating processes, the AR coating might be damaged byjumbo transportation on the conveyer rolls of the large area coater.Some of these breakage problems may be overcome, however, by heattreating (e.g., heat strengthening or thermally tempering) the middlesubstrate. In certain example embodiments, all three substrates may beheat treated.

It has been found that changing the low-e coated surfaces to 2 and 5 asshown in FIG. 3 reduces the solar factor by about 3% points. However,the advantages of this arrangement may be found to outweigh this minorinconvenience. For example, the risk of thermal breakage of the centerlite relate to absorption may be reduced, as there are no low-E coatedsurfaces on the middle substrate. Thus, the center lite surfaces 3 and 4are both available for an AR coating, making an efficient one-step dipcoating possible. Surfaces 3 and 4 are both protected against outsideatmosphere, contamination, cleaning processes, and/or the like. Surfaces1 and 6 are also available to support AR coatings. The FIG. 3 exampleembodiment may be advantageous in that the reduced heat transfer and/orabsorption by the center substrate may reduce the need for heat treatingthis center substrate. Thus, certain example embodiments may involveheat treated (e.g., heat strengthened or thermally tempered) inner andouter substrates with an annealed center substrate. However, differentexample embodiments may involve all three substrates being heat treated.

Antireflective features on a glass substrate may be achieved bydisposing thin film layer stacks on the substrates, and/or by definingrough surfaces (e.g., moth-eye structures) in the glass substratesthemselves. Any suitable thin film coating technique may be used indifferent embodiments of this invention. For example, the sol-gelprocesses are well suited for disposing AR coatings on large surfaces.FIG. 4 plots percent reflectance versus wavelength for AMIRAN(TRADEMARK) coated glass provided by Schott provided on both surfaces ofa 4 mm thick piece of float glass. As can be deduced from FIG. 4, theaverage reflectance in the visible range (e.g., between 380 nm and 780nm) amounts to only 1.3%.

The following table provides the U-value, visible transmission, andg-value of four different triple glaze IGU assemblies (4 mm floatglass/16 mm spacer, Argon filled 90%/4 mm float glass/16 mm spacer,Argon filled 90%/4 mm float glass). The coated surfaces (low-E, with 4%emissivity) are indicated in the first column. The first two exampleassemblies do not include AR coatings, whereas the last two exampleassemblies show the performance of the same assemblies with the abovementioned AR-coating applied.

U-value T_(vis) R_(vis) g-value Uncoated Assembly (W/m²K) (%) (%) (%)Surfaces Low-E on surface 3&5 0.7 70 15 55 1, 2, 4, 6 Low-E on surface2&5 0.7 70 15 53 1, 3, 4, 6 Low-E on surface 3&5, 0.7 73 10 57 1, 6 ARon surface 2&4 Low-E on surface 2&5, 0.7 73 10 55 1, 6 AR on surface 3&4

By applying two AR coatings in a triple glaze unit, the visible lightreflectance of the complete IGU is decreased by about 5% points.Transmittance and solar factor are increased by 3% points and 2% points,respectively. A further reduction in reflectance may be achieved byapplying two further AR-coatings on the remaining uncoated surfacesfacing inside and outside atmosphere.

The low-E coatings need not necessarily be disposed in the same mannerand/or at the same time as the AR coatings. For example, in certainexample embodiments, the AR coating may be PE-CVD deposited or disposedusing a wet technique from a sol, whereas the low-E coating may, forinstance, be sputter deposited. Any suitable low-E coating may be usedin connection with the different example embodiments disclosed herein.An example low-E coating that may be used in connection with certainexample embodiments is shown in FIG. 5.

As shown in FIG. 5, a glass substrate 10 supports an infrared (IR)reflecting layer 55. The IR reflecting layer 55 in the FIG. 5 exampleembodiment comprises Ag. Optional dielectrics are disposed between theIR reflecting layer 55 and the substrate 10. In the FIG. 5 embodiment,these dielectrics include a layer comprising TiO_(x) (e.g., TiO₂ orother suitable stoichiometry) 51, as well as a layer comprising ZnO_(x)(e.g., ZnO₂ or other suitable stoichiometry) 53. The layer comprisingTiO_(x) 51 may help with optical matching, while layer comprisingZnO_(x) 53 may provide a good surface on which the Ag-inclusive IRreflecting layer 55 may be deposited.

One or more layers may be disposed above the IR reflecting layer 55 tohelp protect it, e.g., from oxygen migration during subsequent layerdeposition. For example, a layer comprising Ni and/or Cr 57 which may ormay not be oxidized (or sub-oxidized) may be disposed over andcontacting the IR reflecting layer 55 in certain example embodiments.Further dielectrics may be disposed over the layer comprising Ni and/orCr 57. As shown in the FIG. 5 example, a layer comprising tin oxide(e.g., SnO₂ or other suitable stoichiometry) 59 may be located over thelayer comprising Ni and/or Cr 57, and a protective silicon-inclusivelayer (e.g., including silicon nitride, silicon oxide, siliconoxynitride, and/or the like) 61 may be located over the layer comprisingtin oxide 59. Example thicknesses for the layers shown in the FIG. 5embodiment are provided in the table below.

Preferred More Preferred Example Layer (Å) (Å) (Å) TiO_(x) 150-250170-230 200 ZnO_(x) 125-210 140-195 168 Ag  10-150  65-100 77 NiCrO_(x)12-33 15-30 26 SnO_(x) 195-325 220-300 260 Si_(x)N_(y) (e.g., Si₃N₄) 10-1000  50-500 200

In certain example embodiments, additional dielectrics may be added tothe upper and/or lower portions of the stack (e.g., above and/or belowthe IR reflecting layer). For example, thin layers of or includingtitanium oxide (e.g., TiO₂ or the like) may be added for opticalpurposes, silicon-inclusive layers may be added as barrier layers, etc.

The following table lists performance characteristics for the examplelow-E stack disposed on a single side of a 4 mm thick ExtraClear glasssubstrate (which is commercially available from the assignee of theinstant invention). The “Sample Average” column in the table belowpresents data averaged across three actually-produced samples.

More Sample Preferred Preferred Example Average Transmission Y 87.5-90.588.0-90.0 89.0 88.4 a* −3-0 −2.5-−0.5 −1.5 −1.2 b* −1.3-3.2 −0.6-+2.40.9 0.9 Glass Side 4.2-8.8 5-8 6.5 7.2 Reflectance Y a* −2-+1 −1.5-+0.5−0.5 −0.1 b* −4.7-+1.3 −3.7-+0.3 −1.7 −1.6 Film Side 3.75-8.25 4.5-7.56.0 6.4 Reflectance Y a* −1.5-+1.5 −1-+1 0.0 0.0 b* −3-+3 −2-+2 0.0 −0.5Sheet Resistance 6.4-7.7 6.7-7.5 7.2 — (Rs)

The following table lists performance characteristics for a triple glazeIG unit that includes the example low-E layer stack disposed on surfaces2 and 5 in accordance with an example embodiment. The substrates usedwere 4 mm thick ExtraClear glass substrates. These substrates werespaced apart using 14 mm spacers, with 90% Ar fills in each of thecavities. As above, the “Sample Average” column in the table belowpresents data averaged across three actually-produced samples.

More Sample Preferred Preferred Example Average Transmission Y 70.0-76.071.0-75.0 73.0 71.9 a* −6.7-−0.8 −4.5-−1.5 −3.0 −2.4 b* −0.0-3.0 0.5-2.51.5 1.2 Reflectance Y 13.0-20.0 14.0-19.0 16.0 18.0 a* −3.3-+1.3−2.5-+0.5 −1.0 −1.3 b* −3.3-+1.3 −2.5-+0.5 −1.0 −0.8 U-Value 0.67-0.730.68-0.72 0.70 0.70 g-factor 59.00-65.00 60.00-64.00 62.00 59.80 Normal5.0-11.0  6.0-10.0 8.0 7.4 Emissivity EN410 (%)

In certain example embodiments, a layer comprising titanium oxide (e.g.,TiO₂ or other suitable stoichiometry) may be provided above the layercomprising Ni and/or Cr in the FIG. 5 example coating. The followingtable provides example thicknesses for this example arrangement.

Preferred More Preferred Example Layer (Å) (Å) (Å) TiO_(x) 135-225150-210 180 ZnO_(x) 145-245 165-225 196 Ag 54-92 69-84 73 NiCrO_(x)18-30 20-28 24 TiO_(x) 18-32 21-29 25 SnO_(x) 135-225 150-210 180Si_(x)N_(y) (e.g., Si₃N₄)  10-1000  50-500 256

The following table lists performance characteristics for a triple glazeIG unit that includes the example low-E layer stack from the tableimmediately above disposed on surfaces 2 and 5 in accordance with anexample embodiment. The substrates used were 4 mm thick ExtraClear glasssubstrates. These substrates were spaced apart using 14 mm spacers, with90% Ar fills in each of the cavities. As above, the “Sample Average”column in the table below presents data averaged across threeactually-produced samples. Data for a monolithic coated article also isprovided.

More Preferred Preferred Example Triple IG Unit Transmission Y 70.0-76.071.0-75.0 73.0 a* −6.7-−0.8 −4.5-−1.5 −3.0 b* 0.0-3.0 0.5-2.5 1.5Reflectance Y 13.5-19.5 14.5-18.5 16.5 a* −3.3-+1.3 −2.5-+0.5 −1.0 b*−3.3-+1.3 −2.5-+0.5 −1.0 U-Value 0.67-0.73 0.68-0.72 0.70 g-factor59.00-65.00 60.00-64.00 62.00 Normal  5.0- 11.0  6.0-10.0 8.0 EmissivityEN410 (%) Monolithic Transmission Y 87.5-90.5 88.0-90.0 89.0 a* −3-0 −2.5-−0.5 −1.5 b* −1.35-+3.15 −0.6-+2.4 0.9 Glass Side 4.25-8.75 5-8 6.5Reflectance Y a* −2-+1 −1.5-+0.5 −0.5 b* −4.7-+1.3 −3.7-+0.3 −1.7 FilmSide 3.75-8.25 4.5-7.5 6.0 Reflectance Y a* −1.5-+1.5 −1-+1 0.0 b* −3-+3−2-+2 0.0 Sheet Resistance 6.45-7.95 6.7-7.5 7.2 Rs

The data in the tables above provided data for the FIG. 5 examplecoating and the modification thereto when the coatings were in theannealed (non-heat treated) state. The FIG. 5 example coating and theproposed modifications thereto may be heat treatable in certain exampleembodiments, however. In such cases, a silicon-inclusive layer may beintroduced between the IR reflecting layer and the substrate. Forinstance, a layer comprising silicon nitride, silicon oxide, and/orsilicon oxynitride may be interposed between the IR reflecting layer andthe substrate in heat treatable example embodiments. Such a layer may,for instance, be located over and contacting the substrate in certainexample embodiments. More particularly, in certain example embodiments,the lower dielectric stack (glass/titanium oxide (e.g., TiO₂ or othersuitable stoichiometry)/zinc oxide (e.g., ZnO₂ or other suitablestoichiometry)) may be replaced with layers comprising: glass/siliconnitride (e.g., Si₃N₄ or other suitable stoichiometry)/titanium oxide(e.g., TiO₂ or other suitable stoichiometry)/zinc oxide (e.g., ZnO₂ orother suitable stoichiometry); glass/silicon nitride (e.g., Si₃N₄ orother suitable stoichiometry)/titanium oxide (e.g., TiO₂ or othersuitable stoichiometry)/zinc oxide (e.g., ZnO₂ or other suitablestoichiometry)/titanium oxide (e.g., TiO₂ or other suitablestoichiometry)/zinc oxide (e.g., ZnO₂ or other suitable stoichiometry);or the like. The total dielectric thickness (e.g., below the Ag) mayremain approximately the same (e.g., at or about 38 nm in certainexamples). Delta E* values may be low (e.g., less than or equal to 3.0,more preferably less than or equal to 2.5, still more preferably lessthan or equal to 2.0, and possibly even lower).

In certain example embodiments, some or all of the example layer stackshown in and described in connection with FIG. 5 and the modificationthereto may be replicated one or more times. For instance, in certainexample embodiments, some or all of layers 51, 53, 55, 57, 59, and 61may be provided over the silicon-inclusive layer 61 in one, two, or moresubsequent passes. In certain example embodiments, however, the low-Ecoating may include one and only one IR reflecting layer.

It will be appreciated that other low-E coatings may be used inconnection with different example embodiments. It also will beappreciated that different low-E coatings may be used within a singletriple IG unit assembly. Example low-E coatings are described in, forexample, U.S. Pat. Nos. 7,455,910; 7,771,571; 7,166,359; 7,189,458;7,198,851; 7,419,725; 7,521,096; 7,648,769; 7,964,284; and 8,017,243; aswell as U.S. Publication Nos. 2007/0036986; 2007/0036990; 2007/0128451;2009/0205956; 2009/0324967; 2010/0075155; 2010/0279144; 2010/0295330;2011/0097590; 2011/0117371; 2011/0210656; 2011/0212311; and2011/0262726; and U.S. application Ser. No. 13/064,066, filed on Mar. 3,2011; Ser. No. 13/183,833, filed on Jul. 15, 2011; and Ser. No.13/317,176, filed on Oct. 12, 2011. The entire contents of each of thesepatent documents is hereby incorporated herein by reference. Thus, itwill be appreciated that silver-based and non-silver-based low-Ecoatings may be used in connection with certain example embodiments. Itmay sometimes be advantageous to use non-silver-based low-E coatings fordurability purposes, and/or to provide heat treatable coatings. In somecases, it may be desirable to provide a coating with comparable sheetresistance and emissivity values to those provided above withoutincluding an Ag-based layer. Another example low-E coating that may beused in connection with certain example embodiments is set forth in thetable below.

Preferred More Preferred Example 1 Example 2 Layer (Å) (Å) (Å) (Å)Si_(x)N_(y) (e.g., Si₃N₄)  1-500  10-300 156 156 [bottom-most layer]TiO_(x) (e.g., TiO₂) 15-50  30-40 33 35 ZnO_(x) (e.g., ZnO₂) 70-200 95-125 114 110 TiO_(x) (e.g., TiO₂) 15-50  30-40 33 35 ZnO_(x) (e.g.,ZnO) 70-200  95-125 114 110 Ag 70-120  80-100 90 90 Ni and/or Cr  1-10010-50 30 30 (e.g., NiCrO_(x)) SnO_(x) (e.g., SnO₂) 110-150  115-145 130130 ZnO_(x) (e.g., ZnO₂) 70-200  95-125 109 109 Si_(x)N_(y) (e.g.,Si₃N₄) 115-185  125-155 140 140 ZrOx (e.g., ZrO₂)  1-200 10-80 40 40[top-most layer]

Although certain example embodiments have described 4 mm thick glasssubstrates, different substrate types and/or thicknesses may be usedwithin a given embodiment and in different embodiments. In general,glass substrates may be 2-6 mm thick in different embodiments of thisinvention. It also is noted that a given substrate may be replaced witha laminated stack (e.g., of or including a glass substrate/a polymerbased interlayer such as, for example, PVB or EVA/another glasssubstrate). In such cases, the thickness of a single “pane” in thetriple glaze assembly may be considered thicker and thus may range, forexample, from 2-18 mm. Similarly, the spacing between adjacentsubstrates may be 10-18 mm in certain example embodiments, with anexample spacing being 14 mm.

Although wet coating techniques have been described above as an optionfor coating the substrates with AR coatings, other AR coating techniquesmay be used. For instance, the AR coatings may be sputter deposited incertain example embodiments. Sputter deposited heat treatable ARcoatings are disclosed in, for example, U.S. Publication No.2011/0157703, as well as U.S. application Ser. No. 12/923,838, filed onOct. 8, 2010 and Ser. No. 12/929,481, filed on Jan. 27, 2011, the entirecontents of each of which are hereby incorporated by reference herein.

An example four-layer heat treatable sputter deposited AR coating thatmay be used in connection with certain example embodiments is shown inFIG. 6. This four-layer sputtered AR coatings may include, for example,an index matching and/or stress reducing layer 61, a medium index layer63, a high index layer 65, and a low index layer 67, in that order,moving away from the substrate 10. In certain example embodiments, theindex matching and/or stress reducing layer 61 may comprise siliconoxide or silicon oxynitride, the medium index layer 63 may comprisesilicon oxynitride, the high index layer 65 may comprise niobium oxideand/or titanium oxide, and the low index layer 67 may comprise siliconoxide.

The index matching and/or stress reducing layer 61 may substantiallymatch the index of refraction of the supporting glass substrate 10. By“substantially matches,” it is meant that the refractive index of thelayer is within about 0.2 of the refractive index of the glasssubstrate, more preferably within about 0.1, and most preferably thedifference is no greater than about 0.05 or 0.04. This index matchingand/or stress reducing layer 61 may have a thickness of from about 50 to300 nm, more preferably from about 60 to 120 nm, and most preferablyfrom about 60 to 100 nm. However, a layer having any thicknesssufficient to turn the net stress of the coating into compressive stresswithout significantly degrading the optical and/or physicalcharacteristics of coating may be used in other example embodiments. Theinclusion of an additional index-matching/stress-reducing layer may beadvantageous because a coating including an additional layer with ahigher magnitude of compressive stress has been found to have a loweroverall net stress.

The medium index layer 63 may have a thickness of from about 30 to 150nm, more preferably from about 40 to 80 nm, and most preferably fromabout 50 to 70 nm, with an exemplary thickness range being from about53-65 nm. The medium index layer 63 may have a refractive index fromabout 1.6 to 2.0, more preferably from about 1.65 to 1.95, and mostpreferably from about 1.7 to 1.8 or 1.9.

The high index layer 65 may have a refractive index of from about 2.0 to2.6, more preferably from about 2.1 to 2.5, and most preferably fromabout 2.2 to 2.4. The high index layer 65 may have a thickness of fromabout 50 to 150 nm, more preferably from about 75 to 125 nm, even morepreferably from about 80 to 120 nm, and most preferably from about 85 to105 nm. In other example embodiments, however, this high index layer 65may be thinned in order to reduce the net tensile stress of the ARcoating, e.g., such that it has a thickness of less than about 50 nm, oreven less than about 25 nm in some instances. In further exampleembodiments, the high index layer 65 may comprise a high index materialhaving a lesser tensile stress value, before and/or after heattreatment. In this regard, it may comprise an oxide of niobium in someinstances. In other instances, it may comprise an oxide of titanium. Infurther example embodiments, it may comprise another suitable, highindex material.

The low index layer 67 will have an index of refraction lower than thatof the medium and high index layers 63 and 65, and may even have anindex of refraction lower than that of the index matching and/or stressreducing layer 61. In certain examples, the refractive index of the lowindex layer 67 may be from about 1.3 to 1.6, more preferably from about1.35 to 1.55, and most preferably from about 1.43 to 1.52. Its thicknessmay be from about 40 to 200 nm, more preferably from about 50 to 110 nm,and most preferably from about 60 to 100 nm, with an example thicknessbeing around 80 nm.

In certain example embodiments, the index matching and/or stressreducing layer 61 and the low index layer 67 may have substantially thesame thicknesses. For example, their thicknesses may differ by no morethan about 15 nm, more preferably no more than about 10 nm, and mostpreferably no more than about 5 nm, according to certain exampleembodiments.

Plasma-enhanced chemical vapor deposition (PE-CVD) may be used todispose durable antireflective coatings in certain example embodiments.Such PE-CVD deposited layers may include one or more silicon-inclusiveindex matching layers. For example, the same or similar high/medium/lowindex layer stack as that described above may be used in connection withcertain example embodiments. Some or all of these layers may besilicon-inclusive layers (e.g., silicon oxide, silicon nitride, and/orsilicon oxynitride inclusive layers) selected so as to have indexes ofrefraction that match or substantially match those indicated above forthe like layers. In some cases, silicon carbide or silicon oxycarbideinclusive layers may be provided as protective overcoats.

As alluded to above, certain example embodiments may include heattreatable AR coatings. In such cases, AR coatings may be applied priorto heat treatment, enabling large stock sheets to be coated prior tosizing and/or heat treating. In some cases, the low-E coatings may beheat treatable as well. In such cases, the low-E similarly may beapplied prior to heat treatment, enabling large stock sheets to becoated prior to sizing and/or heat treating. In cases where both heattreatable low-E and AR coatings are used, both surfaces of the substratemay be coated prior to sizing and/or heat treating. The comparativelymore durable sputter deposited and/or PE-CVD deposited coatings mayfacilitate low-E coating processes on the other surfaces of suchsubstrates in certain example embodiments.

It is noted that some embodiments may not necessarily include any ARcoatings.

The spacers disclosed in, for example, U.S. Publication Nos.2009/0120019; 2009/0120036; 2009/0120018; 2009/0120035; and2009/0123694, as well as U.S. application Ser. No. 13/067,419, filed onMay 31, 2011, may be used in connection with different embodiments ofthis invention. The entire contents of each of these patent referencesare hereby incorporated herein by reference.

As used herein, the terms “on,” “supported by,” and the like should notbe interpreted to mean that two elements are directly adjacent to oneanother unless explicitly stated. In other words, a first layer may besaid to be “on” or “supported by” a second layer, even if there are oneor more layers there between.

Tempering typically requires use of temperature(s) of at least about 580degrees C., more preferably of at least about 600 degrees C. and stillmore preferably of at least 620 degrees C. The terms “heat treatment”and “heat treating” as used herein mean heating the article to atemperature sufficient to achieve thermal tempering and/or heatstrengthening of the glass inclusive article. This definition includes,for example, heating a coated article in an oven or furnace at atemperature of at least about 550 degrees C., more preferably at leastabout 580 degrees C., more preferably at least about 600 degrees C.,more preferably at least about 620 degrees C., and most preferably atleast about 650 degrees C. for a sufficient period to allow temperingand/or heat strengthening. This may be for at least about two minutes,or up to about 10 minutes, in certain example embodiments.

Certain example embodiments relate to an insulating glass (IG) unit.First, second, and third substantially parallel spaced apart glasssubstrates are provided, with the first substrate being an outermostsubstrate and with the third substrate being an innermost substrate. Afirst spacer system is disposed around peripheral edges of the first andsecond substrates, with a first cavity being defined between the firstand second substrates. A second spacer system is disposed aroundperipheral edges of the second and third substrates, with a secondcavity being defined between the second and third substrates. First andsecond low-emissivity (low-E) coatings are disposed on interior surfacesof the first and third substrates respectively such that the first andsecond low-E coatings face one another. First and second antireflectivecoatings are disposed on opposing major surfaces of the secondsubstrate. Each said low-E coating comprises, in order moving away fromthe substrate on which it is disposed: a layer comprising titaniumoxide, a layer comprising zinc oxide, an infrared reflecting layercomprising silver, a layer comprising a metal, oxide, or sub-oxide of Niand/or Cr, a layer comprising tin oxide, and a layer comprising siliconnitride.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and/or second cavity(ies) may include Ar,Kr, or SF₆ gas.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, each said substrate may be 2-6 mm thick(e.g., 4 mm thick).

In addition to the features of any one of the previous three paragraphs,in certain example embodiments, the first and second substrates may bespaced apart from one another by 10-18 mm (e.g., 14 mm), and the secondand third substrates may be spaced apart from one another by 10-18 mm(e.g., 14 mm).

In addition to the features of any one of the previous four paragraphs,in certain example embodiments, a third AR coating may be disposed on anoutermost surface of the first substrate.

In addition to the features of the previous paragraph, in certainexample embodiments, a fourth AR coating may be disposed on an outermostsurface of the third substrate.

In addition to the features of any one of the previous six paragraphs,in certain example embodiments, the second substrate may or may not beheat treated.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and third substrates may be heat treated.

In addition to the features of any one of the previous eight paragraphs,in certain example embodiments, the IG unit may have a visibletransmission of at least about 70%, a U-value of less than or equal toabout 0.80 (e.g., less than or equal to about 0.70), and a g-value of atleast about 60.

In addition to the features of the previous paragraph, in certainexample embodiments, the normal emissivity of the IG unit may be betweenabout 6.0 and 8.5 (e.g., about 8.0).

In certain example embodiments, an insulating glass (IG) unit isprovided. First, second, and third substantially parallel spaced apartglass substrates are provided, with the first substrate being anoutermost substrate and with the third substrate being an innermostsubstrate. First and second low-emissivity (low-E) coatings are disposedon interior surfaces of the first and third substrates respectively suchthat the first and second low-E coatings face one another, with eachsaid low-E coating including at least one Ag-based infrared (IR)reflecting layer being sandwiched between one or more dielectric layers.First and second antireflective coatings are disposed on opposing majorsurfaces of the second substrate. The first and third substrates areheat treated and the second substrate is not heat treated.

In certain example embodiments, a method of making an insulating glass(IG) unit is provided. First, second, and third glass substrates areprovided, with the second substrate supporting first and secondantireflective (AR) coatings on opposing major surfaces thereof, withthe first substrate supporting a first low-emissivity (low-E) coating onone major surface thereof, and with the third substrate supporting asecond low-E coating on one major surface thereof. The first, second,and third substrates are oriented in substantially parallel spaced apartrelation to one another using first and second spacer systems, with thefirst spacer system being located around peripheral edges of and spacingapart the first and second substrates and with the second spacer systembeing located around peripheral edges of and spacing apart the secondand third substrates. The first substrate is an outermost substrate andthe third substrate is an innermost substrate. The first and secondlow-E coatings are disposed on interior surfaces of the first and thirdsubstrates respectively such that the first and second low-E coatingsface one another. Each said low-E coating comprises, in order movingaway from the substrate on which is disposed: a layer comprisingtitanium oxide, a layer comprising zinc oxide, an infrared reflectinglayer comprising silver, a layer comprising a metal, oxide, or sub-oxideof Ni and/or Cr, a layer comprising tin oxide, and a layer comprisingsilicon nitride.

In addition to the features of the previous paragraph, in certainexample embodiments, Ar or other suitable gas(es) may be provided to afirst cavity defined between the first and second substrates, and/or toa second cavity defined between the second and third substrates.

In addition to the features of either of the two previous paragraphs,the first substrate may support a third AR coating disposed on anoutermost surface thereof.

In addition to the features of the previous paragraph, in certainexample embodiments, the third substrate may support a fourth AR coatingdisposed on an outermost surface thereof.

In addition to the features of any one of the previous four paragraphs,in certain example embodiments, the second substrate may or may not beheat treated.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and third substrates may be heat treated.

In addition to the features of any one of the previous six paragraphs,in certain example embodiments, the IG unit may have a visibletransmission of at least about 70%, a U-value of less than or equal toabout 0.80, and a g-value of at least about 60.

In addition to the features of any one of the previous seven paragraphs,in certain example embodiments, the normal emissivity of the IG unit maybe about 8.0.

In addition to the features of any one of the previous eight paragraphs,in certain example embodiments, each said AR coating may be a PE-CVDdeposited coating.

In addition to the features of the previous paragraph, in certainexample embodiments, each said low-E coating may be a sputter-depositedcoating.

In addition to the features of any one of the previous ten paragraphs,in certain example embodiments, the AR and low-E coatings may be formedusing different coating techniques.

In certain example embodiments, a method of making an insulating glass(IG) unit is provided. A first low-emissivity (low-E) coating isdeposited on a first substrate. First and second antireflective (AR)coatings are disposed on opposing major surfaces of a second substrate.A second low-E coating is deposited on a third substrate. Either (a) thefirst, second, and third substrates are built into an IG unit, or (b)the first, second, and third substrates are forwarded to a fabricator tobe built into an IG unit. In the built IG unit, the second substrate issandwiched between the first and third substrates such that the firstand second low-E coatings face one another.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and second substrates may be heattreated, and the second substrate may not be heat treated.

In addition to the features of either of the two previous paragraphs,the first and second AR coatings may be disposed on the second substratevia a wet chemical process, and the first and second low-E coatings maybe sputter deposited on the first and third substrates respectively.

In addition to the features of any one of the previous three paragraphs,in certain example embodiments, the first and second AR coatings may bedisposed on the second substrate via a PE-CVD process, and the first andsecond low-E coatings may be sputter deposited on the first and thirdsubstrates respectively.

In addition to the features of any one of the previous four paragraphs,in certain example embodiments, each said low-E coating may comprise, inorder moving away from the substrate on which it is disposed: a layercomprising titanium oxide, a layer comprising zinc oxide, an infraredreflecting layer comprising silver, a layer comprising a metal, oxide,or sub-oxide of Ni and/or Cr, a layer comprising tin oxide, and a layercomprising silicon nitride.

In addition to the features of any one of the previous five paragraphs,in certain example embodiments, each said AR coating may comprise, inorder moving away from the surface on which it is deposited, a mediumindex layer, a high index layer, and a low index layer.

In addition to the features of the previous paragraph, in certainexample embodiments, the medium index layer may comprise siliconoxynitride, the high index layer may comprise niobium oxide and/ortitanium oxide, and the low index layer may comprise silicon oxide.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the medium index layer may have an index ofrefraction of 1.65 to 1.95, the high index layer may have an index ofrefraction of 2.1 to 2.5, and the low index layer may have an index ofrefraction of 1.35 to 1.55.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1-30. (canceled)
 31. An insulating glass (IG) unit, comprising: first,second, and third substantially parallel spaced apart glass substrates,the first substrate being an outermost substrate and the third substratebeing an innermost substrate; a first spacer system disposed aroundperipheral edges of the first and second substrates, a first cavitybeing defined between the first and second substrates; a second spacersystem disposed around peripheral edges of the second and thirdsubstrates, a second cavity being defined between the second and thirdsubstrates; first and second low-emissivity (low-E) coatings disposed oninterior surfaces of the first and third substrates respectively suchthat the first and second low-E coatings face one another; and first andsecond antireflective coatings disposed on opposing major surfaces ofthe second substrate, wherein each said low-E coating comprises, inorder moving away from the substrate on which it is disposed: a layercomprising titanium oxide, a layer comprising zinc oxide, an infraredreflecting layer comprising silver, a layer comprising a metal, oxide,or sub-oxide of Ni and/or Cr, a layer comprising tin oxide, and a layercomprising silicon nitride, and wherein the IG unit has a visibletransmission of at least about 70%, a U-value of less than or equal toabout 0.80, and a g-value of at least about
 60. 32. The IG unit of claim1, wherein the first and/or second cavity(ies) include(s) Ar, Kr, or SF₆gas.
 33. The IG unit of claim 1, wherein each said substrate is 2-6 mmthick.
 34. The IG unit of claim 1, wherein the first and secondsubstrates are spaced apart from one another by 10-18 mm, and whereinthe second and third substrates are spaced apart from one another by10-18 mm.
 35. The IG unit of claim 1, further comprising a third ARcoating disposed on an outermost surface of the first substrate.
 36. TheIG unit of claim 5, further comprising a fourth AR coating disposed onan outermost surface of the third substrate.
 37. An insulating glass(IG) unit, comprising; first, second, and third substantially parallelspaced apart glass substrates, the first substrate being an outermostsubstrate and the third substrate being an innermost substrate; firstand second low-emissivity (low-E) coatings disposed on interior surfacesof the first and third substrates respectively such that the first andsecond low-E coatings face one another, each said low-E coatingincluding at least one Ag-based infrared (IR) reflecting layersandwiched between one or more dielectric layers; and first and secondantireflective coatings disposed on opposing major surfaces of thesecond substrate; and wherein the IG unit has a visible transmission ofat least about 70%, a U-value of less than or equal to about 0.80, and ag-value of at least about 60.